Ice Dmas

Ice Dams Prevention

Ice dams are one of the biggest roof-related nightmares for homeowners in the northern US and Canada. The results of ice dams roof leaks can cost you hundreds, even thousands of dollars to fix. To make matters worse, if you have ice dams and your roof actively leaks, even if you remove the ice and snow off you roof, they will come back the next time it snows.

Image of Ice dams on the roof

In picture above you can see massive ice dams on a roof of a home in Newton, MA. Although this is a fairly modern home, you can see by the size of these ice dams that there is a lot of heat loss through the roof and the roof is not ventilated properly.

What are ice dams and how they form on your roof – quick overview:

Ice dams are ice formations along the eaves (lower drip-edge) of a roof. Ice dams form when snow on the roof is melted by the warm air in the attic space, and water runs down toward the edge of the roof which is not heated, and freezes there. As more and more snow melts and ice along the roof edge grows, it becomes so big that it actually blocks the melted water from running down – creates a dam – hence the name Ice Dams. The water has no where to go, but backwards, under roofing shingles and inside your home.

image of ice dam prevention diagram - how ice dams form

Once water leaks into your house, it saturates the insulation in the attic / walls, wets the sheet-rock on the ceilings and walls, and causes all kinds of structural damage if left untreated.

Removing, preventing and eliminating ice dams:

You can prevent ice dams by doing some of the things listed below. However, before you choose the easiest way out – consider this: Just removing ice dams will remove the effect, but will not solve the problem of why you get ice dams on your roof in the first place.

Things to do to prevent ice dams:

  • Raking a roof or hiring a roofing contractor to remove snow / ice off your roof, before it melts and turn into ice dams.
  • Use electric heat cables to melt the ice dams along the eaves of your roof – requires continuous use of electric power.
  • Use rock-salt or ice melt filled socks spaced on the roof to melt the ice dams – requires frequent replacement of ice melt.
  • Throw calcium chloride onto ice dams and then remove the smaller pieces with a hammer – requires a lot of calcium chloride ice melt and you would actually to either get up on the roof or work off a ladder.
  • Installing Ice Belts along the eaves of the roof to prevent ice form forming or penetrating the roof by going under the shingles. May not work well on low slope roof and if ice dams start forming above ice belt.
  • Improving insulation of the attic space to reduce amount of heat loss from your living space – this will reduce a the size of ice dams and the speed with which the form.
  • Improving the roof ventilation, so that warm air from your living space would escape before it melted the snow on the roof.
  • Installing a metal roof or a flat / low-slope roofing membrane on your roof, will also solve the the ice-dam roof leaks, if / when other ice dam prevention methods do not work.

The ice dam prevention methods listed above go from immediate short term solution to a slow and more expensive long-term / permanent solution for ice dams.

Optimal solution to prevent ice dams:

Basically to avoid ice dams it’s best to have properly working roof ventilation and adequate attic insulation. A thick layer of insulation – for most states R-30 insulation is required for any new construction or restoration, and R-49 insulation is optimal to prevent most heat loss. Having a well working soffit / ridge ventilation system will remove and warm air that leaked through your insulation, for a heated interior space of your home.

If insulation is loose-laid blown-in or fiber-glass insulation positioned between the joists, make sure that air intake at the soffits is not blocked by insulation. If insulation is installed between roof rafters, make sure there are baffles running all the way from roof eaves to the ridge vent. This is especially important if you have cathedral ceilings and have no access to the insulation, once the inside is finished.

In some cases, it is impossible or very expensive to improve the insulation / ventilation of your attic space. This is a common problem with gambler roofs, roofs with pitch change, and shed-type additions to the house. In these case proper ventilation either does not exist at all or cannot function properly because of pitch change.

Best solution for these types of roofs is to have a metal roof or low-slope roofing membrane installed. This will permanently stop your roof leaks, and will give you time to figure out the insulation / ventilation.

Temporary solutions for ice dam roof leaks:

The best way to prevent the ice dams temporarily (until you can figure out a permanent solution) is to rake your roof before major ice dams have time to form. It is best to rake right after the snow stops, or even during the snow-fall. This will not let the ice dams form and will save you money on interior repair and will not wet your insulation, which makes ice dam problems only more severe. However this is not the solution for the long-term, as you can’t constantly rake your roof – I’m sure you have other things to do in life.

You can also use rock-salt, snow melt, snow-melt filled socks or electric heating cables to remove ice dams, but this is either costly and involved or just a costly way to deal with ice dams.

Lastly – you can hire a roofing contractor to get rid of your ice dams, but this is even more expensive than all the options listed above, and by the time you hire a contractor, the ice dams have already formed and your roof already leaked and the damage has been done – don’t let things come to this – prevent ice dams before they happen.

Permanent Ice Dams-proof roofing materials:

If your house has a medium to steep roof slope, and you are experiencing major ice-dams related roof leaks, consider getting a standing seam roofing system installed on your roof. The design of metal roofs typically prevents ice dams from forming as a metal roof shed ice and snow, and even when ice dams do form, the design of a metal roof will prevent any water from backing up and penetrating the roof, which is the case with asphalt roofing shingles. Do note that most metal roofing systems cannot be installed on low slope roofs (under 3 in 12 roof pitch), and some type of low slope roofing membrane is the only right choice of roofing material.

On low-slope roof with roof pitch less than 3 in 12 inches, such as many shed dormers or upper portions of most gambrel roofs, installing a flat roofing membrane will eliminate ice dam roof leaks. Wide roof rolls and hot-air welded overlaps (seams), will prevent any water from getting under the roofing systems and leaking inside your home.

Both metal roofs and PVC flat roofs are also Cool Roof rated roofing materials and will help keeping your homes cooler in the summer. They are also considered permanent roofing systems, as they offer a lifetime material warranties for residential homes, and do last that long.

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Written by admin

November 3rd, 2012 at 2:48 pm

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2 Responses to 'Ice Dams Prevention'

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  1. One key point to remember is to never use an open flame to remove ice dams. Each year hundreds of homes catch on fire this way.

    I was just reminded of this fact by a local fire here. Be smart, be safe.

    Jay Martin

    31 Dec 11 at 2:26 pm

  2. Ice damming is a major problem that most homeowners are unaware of until they have a leak which in most cases is significant. I like that most don’t know as it keeps me in business but if more homeowners would be proactive they’d save themselves and the insurance companies ALOT of money. Hire a professional.

    See you guys at the Roofing Expo in Orlando in Feb.

    Chuck Hester
    toll free: 855 790 7663

    Chuck Hester

    4 Jan 12 at 5:55 am

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